Robert Colvile is a writer and senior comment editor at the Telegraph, who cares more about politics and policy than is probably healthy - for his newest pieces, please see here. He tweets as @rcolvile.

Would a 'no coalitions' pledge be bold, insanely bold or just insane?

Waving goodbye? David Cameron is considering going it alone after the 2015 election (Pic: Eddie Mulholland)

The Tories have a cunning plan. No, not to rebrand themselves the Workers' Party, but to campaign at the next election on a no-coalitions platform. The nation, they believe, longs for the smack of firm government. So in 2015, the party will campaign on a simple premise: vote Dave, or get Ed.

This, at least, was the idea set out to our own Benedict Brogan, and relayed in his column this morning. Since then, the reaction has been… well, mixed would be putting it politely. Philip Johnston has already outlined some of the practical difficulties. But for my money, it's the politics of the move that would be the real drawback.

First things first. The rationale behind this scheme is that the voters are just as tired of the Coalition as the ministers within it – polls suggest that a solid majority want a majority government.

And that's fine. But how many of them actually want a Tory majority government?

It pains me to write this, given my tribal and intellectual loyalty to the Conservative Party, but its single biggest problem hasn't gone away. Ever since 1992, the main truth of British politics has been that a lot of voters don't like the Tories very much – more, in fact, than any other party. Even in 2010, at the depth of Labour's unpopularity, there was still a sufficiently strong anti-Tory sentiment to keep the party from outright power. Today, 33 per cent of voters say they would never, ever vote Conservative, against just 24 per cent for Labour.

The next problem is where those voters lie on the political spectrum. Yes, there are an awful lot of disillusioned Right-wingers who have turned their backs on the Tories and embraced Ukip. But the eternal truth of British politics is that elections are won on the centre ground. That was the case in 2010: the numbers show that the Tories failed to win not because they had changed, but because they hadn't changed enough.

To a rather large proportion of the population, then, the idea of what Benedict's column calls "Tory radicalism seasoned with Lib Dem moderation" was actually a pretty appealing combination. Maybe they've become disillusioned since then. But it's hard to make the leap from that to arguing that what such voters are crying out for is a Tory party that will do the properly, zealously Right-wing things that the Libs have been stopping them doing.

If Cameron does pursue the no-coalitions idea, then, there are two things he needs to do for it to succeed. The first is to present a vision of what outright Tory government would mean that doesn't come across as a red-meat blend of repealing the Human Rights Act, privatising the NHS, and banning immigration. He needs, in short, to make it clear to those floating centre-ground voters that he won't be leaving a coalition with Nick Clegg only to enter one with Peter Bone.

And the second task? Simple: to follow Iain Martin's advice, and pound away at Ed Miliband's credentials until there is no floating voter who can possibly see him as prime ministerial material. Making the election a personality contest between Dave and Ed is, and always has been, the Tories' best hope of victory. But the obstacles stacked against Cameron's chances – in terms of the constituency boundaries, the lingering negatives surrounding the Tory brand, and all the rest of it – mean that he can't afford to leave Miliband with a single shred of credibility. Otherwise, he may wake up on May 8, 2015 and realise that his tactical masterstroke has handed Labour the keys to No 10.